This study examines the relationship of nitric oxide, systemic and renal vascular resistances, and arterial pressure in patients with advanced liver disease before and after liver transplantation. Our studies-to-date demonstrate major changes in circadian pressure regulation and vascular hemodynamics after tranplantation using immunosuppression based upon cyclosporine A. Remarkably, circulating nitric oxide levels are not reduced after transplantation, although levels of cyclic GMP (the second messenger of nitric oxide) are reduced, both in comparison to normal levels and to levels in patients with cirrhosis. These data emphasize the separation between plasma NO and tissue levels of receptor activation in this condition, which appear central to changes in blood pressure after solid organ transplantation.